Bowling balls are provided with holes, as by drilling into the bowling ball, the holes serving as finger and thumb grips for a bowler to hold and throw the ball down an alley at bowling pins. These holes, for a conventional bowling ball, include holes for receiving the thumb, middle finger and ring finger of a bowler. Holes in a bowling ball are sized to provide a comfortable fit with fingers of a bowler. The holes are also spaced apart at a distance appropriate the spread of the bowler's fingers. This spread is determined by distances between the base of a bowler's thumb and the proximal interphalangeal joint (the joint nearest the palm) of the middle and ring finger of the user of the bowling ball. Uniformly throughout the prior art, the bowler inserts his thumb into the ball up to the base of the thumb and fingers into the ball up to the proximal interphalangeal joint. As such, a thumb hole is typically three inches or more in depth, and the finger holes are typically two inches or more in depth.
In order to knock down as many pins as possible, most bowlers seek to obtain a pronounced hook on the path of the ball, this type of delivery geometrically providing more rotation creating more revolutions and thereby the most pin action, or mixing of the pins after they are struck by the ball. To make the ball hook, effective contact between the fingers and the ball is necessary to deliver the ball in a manner such as to impart a lifting and twisting action on the ball, causing it to spin as it rolls down the lane.
Various finger inserts and other measures have been devised for use with bowling balls, primarily to enable an improved spin and a more effective hook. In general, the prior art insert devices have been used in combination with conventional drilled holes, which as stated typically extend to a depth of two inches or more for fingers and three inches or more for thumbs. As a result, contact of the fingers and thumb within the ball occurs the length of the fingers up to the proximal interphalangeal joint and length of the thumb within a respective finger or thumb hole so that contact with finger and thumb tips is not predominant.